How to include external font in WPF application without installing it

I tried this code 

  System.Drawing.Text.PrivateFontCollection privateFonts = new    System.Drawing.Text.PrivateFontCollection();
  privateFonts.AddFontFile("C:\\Documents and Settings\\somefont.ttf");
  System.Drawing.Font font = new Font(privateFonts.Families[0], 12);
  this.label1.Font = font;

It working correctly in Windows Form Application but not in WPF.

c# wpf fonts
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